They said the two U.N. vehicles were badly damaged in the explosion. It was not clear how recently the mine had been planted. But the whole border region is thick with mines, cluster bombs and other unexploded ordnance left over from last year's war between Israel and Hezbollah guerrillas, and previous conflicts. Israel has refused to give the UN the maps that show the location of the mines, despite repeated requests.

Residents said ammunition in one U.N. troop carrier exploded after the landmine detonated.

A U.N. spokesman said he was checking the report.

There was no-one immediately available to comment at Spain's Defense Ministry in Madrid.

Picture: Spanish UNIFIL soldiers patrol the streets of the southern Lebanese , near the Israel-Lebanon border

Update: 8:00 PM Beirut time

The national new Agency has reported that the number of soldiers killed has risen to 5 and number of wounded to 6. UNIFIL described the incident as extremely serious and dangerous.

The blast was caused by a large bomb ( not a mine ) according to UNIFIL , that has been recently planted and was remotely activated . No word on the weight of the bomb.

Hezbollah has condemned the incident which it described as being "suspicious"

Sources: Reuters, DPA, Ya Libnan